This appears to be a mismatch between Unity and the Android SDK, and reverting to an older version of the Android SDK should apperently solve this problem. However, as described in this thread over at Unity Answers – there is an “easy” solution to this problem.

In the end, I have prepared a few pointers on issues that for some reason I experience and forget how to solve. Part of the reason why I get confused, is because of bad error messages from Unity.

When installing the Android SDK – make sure that there is no “space” or special characters in the installpath. The default install location will not work, you have to set it manually.

Remeber to set the path of the Android SDK “Edit -> Preferences -> External Tool”

Remember to set the password for the keystore “Edit -> Project Setting -> Player -> Publishing Settings”

If you are using different computers to build the Android – remember to set the correct path to the keystore (This changes if you commit the changes on different computers) “Edit -> Project Setting -> Player -> Publishing Settings”